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<h1>Source code for matplotlib.units</h1><div class="highlight"><pre>
<span></span><span class="sd">"""</span>
<span class="sd">The classes here provide support for using custom classes with</span>
<span class="sd">Matplotlib, e.g., those that do not expose the array interface but know</span>
<span class="sd">how to convert themselves to arrays. It also supports classes with</span>
<span class="sd">units and units conversion. Use cases include converters for custom</span>
<span class="sd">objects, e.g., a list of datetime objects, as well as for objects that</span>
<span class="sd">are unit aware. We don't assume any particular units implementation;</span>
<span class="sd">rather a units implementation must provide the register with the Registry</span>
<span class="sd">converter dictionary and a `ConversionInterface`. For example,</span>
<span class="sd">here is a complete implementation which supports plotting with native</span>
<span class="sd">datetime objects::</span>
<span class="sd"> import matplotlib.units as units</span>
<span class="sd"> import matplotlib.dates as dates</span>
<span class="sd"> import matplotlib.ticker as ticker</span>
<span class="sd"> import datetime</span>
<span class="sd"> class DateConverter(units.ConversionInterface):</span>
<span class="sd"> @staticmethod</span>
<span class="sd"> def convert(value, unit, axis):</span>
<span class="sd"> 'Convert a datetime value to a scalar or array'</span>
<span class="sd"> return dates.date2num(value)</span>
<span class="sd"> @staticmethod</span>
<span class="sd"> def axisinfo(unit, axis):</span>
<span class="sd"> 'Return major and minor tick locators and formatters'</span>
<span class="sd"> if unit!='date': return None</span>
<span class="sd"> majloc = dates.AutoDateLocator()</span>
<span class="sd"> majfmt = dates.AutoDateFormatter(majloc)</span>
<span class="sd"> return AxisInfo(majloc=majloc,</span>
<span class="sd"> majfmt=majfmt,</span>
<span class="sd"> label='date')</span>
<span class="sd"> @staticmethod</span>
<span class="sd"> def default_units(x, axis):</span>
<span class="sd"> 'Return the default unit for x or None'</span>
<span class="sd"> return 'date'</span>
<span class="sd"> # Finally we register our object type with the Matplotlib units registry.</span>
<span class="sd"> units.registry[datetime.date] = DateConverter()</span>
<span class="sd">"""</span>
<span class="kn">from</span> <span class="nn">decimal</span> <span class="kn">import</span> <span class="n">Decimal</span>
<span class="kn">from</span> <span class="nn">numbers</span> <span class="kn">import</span> <span class="n">Number</span>
<span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>
<span class="kn">from</span> <span class="nn">numpy</span> <span class="kn">import</span> <span class="n">ma</span>
<span class="kn">from</span> <span class="nn">matplotlib</span> <span class="kn">import</span> <span class="n">cbook</span>
<div class="viewcode-block" id="ConversionError"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionError">[docs]</a><span class="k">class</span> <span class="nc">ConversionError</span><span class="p">(</span><span class="ne">TypeError</span><span class="p">):</span>
<span class="k">pass</span></div>
<span class="k">def</span> <span class="nf">_is_natively_supported</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Return whether *x* is of a type that Matplotlib natively supports or an</span>
<span class="sd"> array of objects of such types.</span>
<span class="sd"> """</span>
<span class="c1"># Matplotlib natively supports all number types except Decimal.</span>
<span class="k">if</span> <span class="n">np</span><span class="o">.</span><span class="n">iterable</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="c1"># Assume lists are homogeneous as other functions in unit system.</span>
<span class="k">for</span> <span class="n">thisx</span> <span class="ow">in</span> <span class="n">x</span><span class="p">:</span>
<span class="k">if</span> <span class="n">thisx</span> <span class="ow">is</span> <span class="n">ma</span><span class="o">.</span><span class="n">masked</span><span class="p">:</span>
<span class="k">continue</span>
<span class="k">return</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">thisx</span><span class="p">,</span> <span class="n">Number</span><span class="p">)</span> <span class="ow">and</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">thisx</span><span class="p">,</span> <span class="n">Decimal</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">Number</span><span class="p">)</span> <span class="ow">and</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">Decimal</span><span class="p">)</span>
<div class="viewcode-block" id="AxisInfo"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.AxisInfo">[docs]</a><span class="k">class</span> <span class="nc">AxisInfo</span><span class="p">:</span>
<span class="sd">"""</span>
<span class="sd"> Information to support default axis labeling, tick labeling, and limits.</span>
<span class="sd"> An instance of this class must be returned by</span>
<span class="sd"> `ConversionInterface.axisinfo`.</span>
<span class="sd"> """</span>
<span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">majloc</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">minloc</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span>
<span class="n">majfmt</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">minfmt</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">label</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span>
<span class="n">default_limits</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> majloc, minloc : Locator, optional</span>
<span class="sd"> Tick locators for the major and minor ticks.</span>
<span class="sd"> majfmt, minfmt : Formatter, optional</span>
<span class="sd"> Tick formatters for the major and minor ticks.</span>
<span class="sd"> label : str, optional</span>
<span class="sd"> The default axis label.</span>
<span class="sd"> default_limits : optional</span>
<span class="sd"> The default min and max limits of the axis if no data has</span>
<span class="sd"> been plotted.</span>
<span class="sd"> Notes</span>
<span class="sd"> -----</span>
<span class="sd"> If any of the above are ``None``, the axis will simply use the</span>
<span class="sd"> default value.</span>
<span class="sd"> """</span>
<span class="bp">self</span><span class="o">.</span><span class="n">majloc</span> <span class="o">=</span> <span class="n">majloc</span>
<span class="bp">self</span><span class="o">.</span><span class="n">minloc</span> <span class="o">=</span> <span class="n">minloc</span>
<span class="bp">self</span><span class="o">.</span><span class="n">majfmt</span> <span class="o">=</span> <span class="n">majfmt</span>
<span class="bp">self</span><span class="o">.</span><span class="n">minfmt</span> <span class="o">=</span> <span class="n">minfmt</span>
<span class="bp">self</span><span class="o">.</span><span class="n">label</span> <span class="o">=</span> <span class="n">label</span>
<span class="bp">self</span><span class="o">.</span><span class="n">default_limits</span> <span class="o">=</span> <span class="n">default_limits</span></div>
<div class="viewcode-block" id="ConversionInterface"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionInterface">[docs]</a><span class="k">class</span> <span class="nc">ConversionInterface</span><span class="p">:</span>
<span class="sd">"""</span>
<span class="sd"> The minimal interface for a converter to take custom data types (or</span>
<span class="sd"> sequences) and convert them to values Matplotlib can use.</span>
<span class="sd"> """</span>
<div class="viewcode-block" id="ConversionInterface.axisinfo"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionInterface.axisinfo">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">axisinfo</span><span class="p">(</span><span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="sd">"""Return an `.AxisInfo` for the axis with the specified units."""</span>
<span class="k">return</span> <span class="kc">None</span></div>
<div class="viewcode-block" id="ConversionInterface.default_units"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionInterface.default_units">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">default_units</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="sd">"""Return the default unit for *x* or ``None`` for the given axis."""</span>
<span class="k">return</span> <span class="kc">None</span></div>
<div class="viewcode-block" id="ConversionInterface.convert"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionInterface.convert">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">convert</span><span class="p">(</span><span class="n">obj</span><span class="p">,</span> <span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Convert *obj* using *unit* for the specified *axis*.</span>
<span class="sd"> If *obj* is a sequence, return the converted sequence. The output must</span>
<span class="sd"> be a sequence of scalars that can be used by the numpy array layer.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="n">obj</span></div>
<div class="viewcode-block" id="ConversionInterface.is_numlike"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.ConversionInterface.is_numlike">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">is_numlike</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> The Matplotlib datalim, autoscaling, locators etc work with scalars</span>
<span class="sd"> which are the units converted to floats given the current unit. The</span>
<span class="sd"> converter may be passed these floats, or arrays of them, even when</span>
<span class="sd"> units are set.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">np</span><span class="o">.</span><span class="n">iterable</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="k">for</span> <span class="n">thisx</span> <span class="ow">in</span> <span class="n">x</span><span class="p">:</span>
<span class="k">if</span> <span class="n">thisx</span> <span class="ow">is</span> <span class="n">ma</span><span class="o">.</span><span class="n">masked</span><span class="p">:</span>
<span class="k">continue</span>
<span class="k">return</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">thisx</span><span class="p">,</span> <span class="n">Number</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">Number</span><span class="p">)</span></div></div>
<div class="viewcode-block" id="DecimalConverter"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.DecimalConverter">[docs]</a><span class="k">class</span> <span class="nc">DecimalConverter</span><span class="p">(</span><span class="n">ConversionInterface</span><span class="p">):</span>
<span class="sd">"""Converter for decimal.Decimal data to float."""</span>
<div class="viewcode-block" id="DecimalConverter.convert"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.DecimalConverter.convert">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">convert</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Convert Decimals to floats.</span>
<span class="sd"> The *unit* and *axis* arguments are not used.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> value : decimal.Decimal or iterable</span>
<span class="sd"> Decimal or list of Decimal need to be converted</span>
<span class="sd"> """</span>
<span class="c1"># If value is a Decimal</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">Decimal</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">float</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="c1"># assume x is a list of Decimal</span>
<span class="n">converter</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">asarray</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">ma</span><span class="o">.</span><span class="n">MaskedArray</span><span class="p">):</span>
<span class="n">converter</span> <span class="o">=</span> <span class="n">ma</span><span class="o">.</span><span class="n">asarray</span>
<span class="k">return</span> <span class="n">converter</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">dtype</span><span class="o">=</span><span class="nb">float</span><span class="p">)</span></div>
<div class="viewcode-block" id="DecimalConverter.axisinfo"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.DecimalConverter.axisinfo">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">axisinfo</span><span class="p">(</span><span class="n">unit</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="c1"># Since Decimal is a kind of Number, don't need specific axisinfo.</span>
<span class="k">return</span> <span class="n">AxisInfo</span><span class="p">()</span></div>
<div class="viewcode-block" id="DecimalConverter.default_units"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.DecimalConverter.default_units">[docs]</a> <span class="nd">@staticmethod</span>
<span class="k">def</span> <span class="nf">default_units</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">axis</span><span class="p">):</span>
<span class="c1"># Return None since Decimal is a kind of Number.</span>
<span class="k">return</span> <span class="kc">None</span></div></div>
<div class="viewcode-block" id="Registry"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.Registry">[docs]</a><span class="k">class</span> <span class="nc">Registry</span><span class="p">(</span><span class="nb">dict</span><span class="p">):</span>
<span class="sd">"""Register types with conversion interface."""</span>
<div class="viewcode-block" id="Registry.get_converter"><a class="viewcode-back" href="../../api/units_api.html#matplotlib.units.Registry.get_converter">[docs]</a> <span class="k">def</span> <span class="nf">get_converter</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">x</span><span class="p">):</span>
<span class="sd">"""Get the converter interface instance for *x*, or None."""</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="s2">"values"</span><span class="p">):</span>
<span class="n">x</span> <span class="o">=</span> <span class="n">x</span><span class="o">.</span><span class="n">values</span> <span class="c1"># Unpack pandas Series and DataFrames.</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">ndarray</span><span class="p">):</span>
<span class="c1"># In case x in a masked array, access the underlying data (only its</span>
<span class="c1"># type matters). If x is a regular ndarray, getdata() just returns</span>
<span class="c1"># the array itself.</span>
<span class="n">x</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">ma</span><span class="o">.</span><span class="n">getdata</span><span class="p">(</span><span class="n">x</span><span class="p">)</span><span class="o">.</span><span class="n">ravel</span><span class="p">()</span>
<span class="c1"># If there are no elements in x, infer the units from its dtype</span>
<span class="k">if</span> <span class="ow">not</span> <span class="n">x</span><span class="o">.</span><span class="n">size</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_converter</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">array</span><span class="p">([</span><span class="mi">0</span><span class="p">],</span> <span class="n">dtype</span><span class="o">=</span><span class="n">x</span><span class="o">.</span><span class="n">dtype</span><span class="p">))</span>
<span class="k">for</span> <span class="bp">cls</span> <span class="ow">in</span> <span class="nb">type</span><span class="p">(</span><span class="n">x</span><span class="p">)</span><span class="o">.</span><span class="vm">__mro__</span><span class="p">:</span> <span class="c1"># Look up in the cache.</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span><span class="p">[</span><span class="bp">cls</span><span class="p">]</span>
<span class="k">except</span> <span class="ne">KeyError</span><span class="p">:</span>
<span class="k">pass</span>
<span class="k">try</span><span class="p">:</span> <span class="c1"># If cache lookup fails, look up based on first element...</span>
<span class="n">first</span> <span class="o">=</span> <span class="n">cbook</span><span class="o">.</span><span class="n">safe_first_element</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="k">except</span> <span class="p">(</span><span class="ne">TypeError</span><span class="p">,</span> <span class="ne">StopIteration</span><span class="p">):</span>
<span class="k">pass</span>
<span class="k">else</span><span class="p">:</span>
<span class="c1"># ... and avoid infinite recursion for pathological iterables for</span>
<span class="c1"># which indexing returns instances of the same iterable class.</span>
<span class="k">if</span> <span class="nb">type</span><span class="p">(</span><span class="n">first</span><span class="p">)</span> <span class="ow">is</span> <span class="ow">not</span> <span class="nb">type</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_converter</span><span class="p">(</span><span class="n">first</span><span class="p">)</span>
<span class="k">return</span> <span class="kc">None</span></div></div>
<span class="n">registry</span> <span class="o">=</span> <span class="n">Registry</span><span class="p">()</span>
<span class="n">registry</span><span class="p">[</span><span class="n">Decimal</span><span class="p">]</span> <span class="o">=</span> <span class="n">DecimalConverter</span><span class="p">()</span>
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